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Question
Without using trigonometric tables, prove that:
cosec272° − tan218° = 1
Solution
LHS = cosec272° − tan218°
= cosec2 (`90^circ - 18^circ`) - tan2 `18^circ`
= `sec^2 18^circ` - tan2 `18^circ`
= 1
= RHS
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